Structure and properties of the LaCuO[sub 3[minus][delta]] perovskites

Journal Article · Tue Jun 01 04:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.47.15269· OSTI ID:6611896

Bringley, J F; Scott, B A; La Placa, S J; McGuire, T R; Mehran, F ^[1]; McElfresh, M W ^[2]; Cox, D E ^[3]

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1. IBM Research Division, Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (United States)
2. Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States)
3. Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (United States)

The high-pressure synthesis and electric and magnetic properties of the LaCuO[sub 3[minus][delta]] system have been studied. The copper valence can be varied in this oxygen-defect perovskite almost continuously from +3 to +2, and three distinct ordered phases are observed over its 0.0[le][delta][le]0.5 stability field. A tetragonal phase exists over the composition range 0.0[lt][delta][le]0.2, and the structure of a sample with [delta]=0.05 was refined by high-resolution synchrotron powder x-ray diffraction in space group [ital P]4/[ital m], with [ital a]=3.818 97(4), [ital c]=3.972 58(6), and [ital R]=0.0812. The tetragonal phase and also a monoclinic form stable between 0.2[le][delta][le]0.4 are metallic with room-temperature resistivities of (1.0--3.0)[times]10[sup [minus]3] [Omega] cm. The phase is orthorhombic for larger [delta], becoming an insulator as [delta][r arrow]0.5. Superconductivity was not observed in any of the metallic samples. Ferromagnetic behavior is observed in the tetragonal materials, but the moment disappears at the [delta][congruent]0.2 phase boundary. The small moment is attributed to the existence of a canted antiferromagnetic array in the tetragonal phase. The results are discussed within the contexts of schematic band models and rationalized in terms of one in which the Fermi level moves through partially overlapping copper 3[ital d][sub [ital x]][sup 2][minus][ital y][sup 2] and oxygen [pi](2[ital p][sub [perpendicular]])[sup *] bands as [delta] increases.

• DOE Contract Number: FG02-90ER45427; AC02-76CH00016
• OSTI ID: 6611896
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 47:22; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRONIC STRUCTURE
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MAGNETIC PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SUPERCONDUCTIVITY
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS